专家论藻类学的新前沿

随着可供利用的陆生资源的日益枯竭以及系统生物学与整合生物技术的兴起,藻类学研究正面临着许多前所未有的挑战与机遇。在312次香山科学会议——《藻类学的新前沿》上,与会专家围绕“系统生物学时代的藻类学研究”、“面向资源环境新需求的藻类生物技术”、“藻类学科和藻类产业的可持续发展”、“藻类与环境”等关键问题,进行了深入的探讨。     

Importance of basic research in applied phycology

Utilization of algae has extended considerably from the middle of this century, with the consequence of more and more applied research in various directions and fields, the most important of which deals with phycocolloid production and algal cultivation to provide raw material and foodstuff. It is noteworthy that this research can not avoid the use of knowledge obtained by basic research; applied phycology is especially indebted to basic research in adopting biotechnologies which are typically coming from basic research. In counterpart, such a situation is beneficial to basic research. According to the dependence of applied phycology to basic research and the fact that restricted research programs only are nowadays financially supported, the fate of all research seems to be questionable.     

Amphidoma parvula (Amphidomataceae), a new planktonic dinophyte from the Argentine Sea

Amphidoma is an old though poorly studied thecate dinophyte that has attracted attention recently as a potential producer of azaspiracids (AZA), a group of lipophilic phycotoxins. A new species, Amphidoma parvula, sp. nov. is described from the South Atlantic shelf of Argentina. With a Kofoidean thecal plate pattern Po, cp, X, 6′, 6′′, 6C, 5S, 6′′′, 2′′′′, the cultivated strain H-1E9 (from which the type material of Am. parvula, sp. nov. was prepared) shared the characteristic plate arrangement of Amphidoma each with six apical, precingular and postcingular plates. Amphidoma parvula, sp. nov. differs from other species of Amphidoma by a characteristic combination of small size (10.7–13.6 µm in length), ovoid shape, high length ratio between epitheca and hypotheca, and small length ratio between apical and precingular plates. Other morphological details, such as the number and arrangement of sulcal plates and the fine structure of the apical pore complex support the close relationship between Amphidoma and the other known genus of Amphidomataceae, Azadinium. However, Am. parvula, sp. nov. lacks a ventral pore, a characteristically structured pore found in all contemporary electron microscopy studies of Amphidoma and Azadinium. As inferred from liquid chromatography coupled with tandem mass spectrometry, Am. parvula, sp. nov. did not produce AZA in measurable amounts. Molecular phylogenetics confirmed the systematic placement of Am. parvula, sp. nov. in Amphidoma (as sister species of Amphidoma languida) and the Amphidomataceae. The results of this study have improved the knowledge of Amphidomataceae biodiversity.     

缺氮胁迫下雨生红球藻虾青素积累过程中的基因组MSAP分析

虾青素具有多种生物学活性,雨生红球藻为天然虾青素的最佳来源,缺氮胁迫会导致雨生红球藻积累虾青素。为了解缺氮条件下雨生红球藻虾青素积累的分子机制,该研究通过对雨生红球藻进行缺氮胁迫,结合MSAP法,研究了雨生红球藻在缺氮胁迫下虾青素积累过程中基因组甲基化水平的变化,结果表明:缺氮胁迫0~72 h期间,雨生红球藻生长速度减慢,而虾青素积累主要发生在缺氮处理12~24 h期间,随后积累速度减慢。同时,对缺氮胁迫0、24、72 h的雨生红球藻基因组DNA进行甲基化敏感扩增多态性分析,共得到了291个甲基化多态性位点,其中发生甲基化变化的位点在0~24 h和24~72 h分别占总位点的29.90%和53.95%。在缺氮胁迫24 h处DNA半甲基化率最大(为12.71%),全甲基化率最低(为26.80%);缺氮胁迫72 h处DNA全甲基化率最高(为28.52%),半甲基化率最低(为1.72%)。这表明DNA甲基化调节方式的改变是虾青素积累过程中的一种重要调控模式。     

Algal communities near Cape Maclear,southern Lake Malaŵi,Africa

Algal communities were compared among benthic and net plankton samples from Cape Maclear, Lake Malai. In the cool mixing season (from May to August), rocks were overgrown byCladophora orCalothrix, accompanied by the diatomsRhopalodia, Cymbella, andNavicula. These diatoms, together withEpithemia andCocconeis, were epiphytic onCladophora and macrophytes. In sandy areas, the common diatoms wereRhopalodia, Fragilaria, Epithemia, Navicula, Surirella, andMelosira.In all phytoplankton samples, taken with a 10 µm mesh net, cyanophyte cells were the most common (70 to 80%), especially those ofOscillatoria. Biomass, however, was dominated byPeridinium from November to April and byAnabaena andOscillatoria from September to April when the mixolimnion was stratified. Among the chlorophytes,Oedogonium was the most common, especially from May into December whenPleodorina became more common.Diatoms dominated the biomass in the mixing season (May to September):Stephanodiscus in May, followed byMelosira nyassensis and lanceolateNitzschia species from mid-June through August. For the rest of the year the epilimnion was stratified and theseNitzschia species were virtually the only diatoms present.Benthic and planktonic communities share few taxa: benthic taxa never made up more than 2% of cells in offshore tows. This conclusion contrasts with previous reports, especially regardingSurirella. Consequently, an abundance of benthic taxa in sediment cores may be interpreted as lower lake level if sediment redistribution can be excluded. The seasonality of the planktonic diatoms is compatible with current ecological hypotheses, and therefore increases their value as paleolimnological indicators.     

Biodiversity and application of microalgae

The algae are a polyphyletic, artificial assemblage of O₂-evolving, photosynthetic organisms (and secondarily nonphotosynthetic evolutionary descendants) that includes seaweeds (macroalgae) and a highly diverse group of microorganisms known as microalgae. Phycology, the study of algae, developed historically as a discipline focused on the morphological, physiological and ecological similarities of the subject organisms, including the prokaryotic bluegreen algae (cyanobacteria) and prochlorophytes. Eukaryotic algal groups represent at least five distinct evolutionary lineages, some of which include protists traditionally recognized as fungi and protozoa. Ubiquitous in marine, freshwater and terrestrial habitats and possessing broad biochemical diversity, the number of algal species has been estimated at between one and ten million, most of which are microalgae. The implied biochemical diversity is the basis for many biotechnological and industrial applications.